Screening of pervaporation membranes for the separation of methanol-methyl acetate mixtures: An approach based on the conceptual design of the pervaporation-distillation hybrid process

Abstract

In this work, the pervaporation-distillation hybrid process is proposed to accomplish the separation of the azeotropic mixture methanol-methyl acetate.First, the separation performance of four membranes of a medium-high flux (Pervap 2256, Pervap 2255-30, PolyAl TypM1 and PolyAn) is analyzed with the aid the pervaporation separation index (PSI). For the commercial Pervap 2256 membrane, pervaporation experiments were conducted to characterize its separation performance especially at compositions of the mixture around the azeotrope.Then, a novel screening approach, which is based on the overall cost of the separation corresponding to the optimal Hybrid process design, is proposed. For feed compositions in the range 0.1?0.9 mol/mol, several process configurations are optimized varying the compositions of the retentate and distillate streams. Quasi-optimal operation temperatures, with correspond to maximum feasible ones, are 348.15 K for the Pervap membranes and 363.15 K for the PolyAn membranes, respectively. The studied membranes are successfully and consistently classified by their respective total cost. The designs corresponding to PolyAl TypM1 and Pervap 2256 membranes present the lowest overall costs.Finally, detailed costs of the vacuum condensing system were also taken into account for the case of the Pervap 2256 membrane to include the permeate pressure as an optimization variable. The optimal value of the permeate pressure is 100 mbar and the corresponding condensation temperature is about 272 K.